The present invention relates to a pipe bending machine, and more particularly to an arrangement for loading and unloading a pipe bending machine.
Metallic tubes are bent in pipe bending machines either with or without the aid of a bending mandrel. This depends to some extent upon the material of the pipe and upon the degree of bending accuracy that is required. If a mandrel is used, a holder for the mandrel in form of a long rod is inserted into the pipe to be bent, and the bending mandrel is mounted on the rod so as to be located within the pipe. Such bending requires that at the head end of the pipe bending machine where the bending template is located, the pipe to be bent be pushed from in front in axial direction onto the bending mandrel and the rod holding the same, and that it be thereupon engaged by the clamping device of the pipe advancing mechanism of the bending machine. As a general rule, the clamping device is far advanced on the pipe advancing carriage of the machine; after the trailing end of the pipe has been engaged by the clamping device the same is returned with the carriage to a starting position, so that the bending operation can then begin.
If the pipe is being bent without a mandrel, then of course insertion of the pipe from the front end of the machine is not necessary. Instead, the clamping device is retracted and the pipe can then be inserted into the machine from a lateral side thereof, whereupon the clamping device is advanced to engage the pipe and the bending operation then proceeds.
The pipes to be bent are cut to a predetermined length and are taken from a pipe magazine to be sequentially placed into the pipe bending machine. The magazine is located laterally of the machine and to permit bending either with or without a mandrel, meaning that the pipes have to be capable of being inserted from one end of the machine or from one side of the machine, it is known in the prior art to make the magazine slidable lengthwise of the machine. Of course, this requires a relatively complicated construction, among other reasons because provision must be made for insertion of the pre-cut pipes into the magazine itself and to permit the magazine to move lengthwise of the machine. In addition, when the magazine is advanced to the vicinity of the head end of the machine so that the pipes can be inserted lengthwise of the machine for bending with a mandrel, the magazine tends to hinder proper bending because after the bending is partially or totally completed a portion of the pipe extends beyond the bending template and is likely to abut against or be abutted by the movable pipe magazine. To avoid this it is very often necessary, depending upon the shape imparted to a bent pipe, to move the magazine every time an individual pipe is being bent with the aid of a mandrel. Of course, having to move the magazine each and every time a pipe is being bent is time consuming and cumbersome and leads to interruptions in the proper sequence of operations, because the constant to-and-fro movement of the magazine makes it difficult to properly and precisely position the pipes being inserted into the machine.